Paper-bag machine.



W. A. LORENZ.

PAPER BAG MACHINE.

APPLICATION FILED 11111.27, 1909.

1,081,315. Patented Dec. 16,1913.

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PAPER BAG MACHINE.

APPLICATION FILED JAN. 27, 1909.

1,081,315. Patented 11111; 16,1913.

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PAPER BAG MACHINE.

APPLIOATION FILED JAN.27, 1909.

1,081,31 5.. Patented Dec. 16, 1913.

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W. A. LORENZ.

PAPER BAG MACHINE.

APPLICATION FILED 11.27, 1909.

1,081,31 5. Patented Dec. 16, 1913.

5 SHEETB-SHEET 4.

Mi 66.5565 Inventor 7 I Z'ZZz'am .JZTZOTGW/Z W. A. LORENZ.

PAPER BAG MACHINE.

APPLICATION FILED 1111.27, 1909.

Patented Dec. 16, 1913.

5 SHEETS-11311! 5.

7 1 72 $263565 Inventor MZZZ'am JZ. Lorenz CQLUAQBM vuwodmml cm. lumnafou. D C.

UN STATES PATENT OFFICE.

WILLIAM A. LORENZ, OF HARTFORD, CONNECTICUT, ASSIGNOR TO UNION PAPER BAG MACHINE COMPANY, PENNSYLVANIA.

0F PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF PAPER-BAG MACHINE.

Application filed January 27, 1909.

To all whom 2'15 may concern Be it known that I, WILLIAM A. LORENZ, a citizen of the United States of America, residing in the city of Hartford, in the county of Hartford, in the State of Connecticut, have invented a certain new and useful Improvement in Paper-Bag Machines, of which the following is a true and exact description, reference being had to the accompanying drawings, which form a part thereof. H

The present invention relates to the art of making square bottomed, or S O S, bags from bellows sided or tucked paper bag blanks, and particularly to the means employed for forming the diamond folds in such bag blanks.

The primary object of the invention is the provision of simple and effective bag forming mechanism adapted for use in the rapid manufacture of bags with a minimum of trouble and waste due, either to the kink ing of the bag blanks and to the improper formation of fold lines thereon, or to the failure or faulty behavior of the parts of the bag forming mechanism which have heretofore been most apt to give trouble when operated at high speed.

ln carrying out the invention, 1 so form and arrange the mechanism for engaging and turning back the upper ply of the blank, that the turning back mechanism, while engaging the upper ply of the blank at the corners of the diamond square, leaves a por tion of the ply between the main oressfold line of the blank and the portion engaged by said mechanism free to accommodate itself to the stresses set up in it during the folding operation. I also so arrange and operate the turning back mechanism, relative to the blank transporting device or folding bed on which the lower ply of the blank is held, that the free portion of the upper ply in front of the main crossfold line is concaved during the early stages of the fold ing operation. By thus concaving the portion of the upper ply most apt to wrinkle in the folding operation, I am enabled to utilise the rigidity of the blank material elf to prevent the upper ply of the blank from bowing out or kinking in front of the erossfold line duringthe folding operation.

Since with my invention, a considerable portion of the upper ply of the blank in Specification of Letters Patent.

Patented Dec. 16, 1913. Serial No. 474,379.

front of the main crossfold line, not only needs no directrestraint by external means, but is necessarily given freedom to adjust itself, the folding plate or plates against which I may clamp the outer surface of the upper ply of the blank do not extend to, or even close to the main crossfold line of the blank.

By doing away with any extension of the folding plate or plates toward the main crossfold line beyond the amount necessary to form a sullicient clamping base for the box holder or gripping lingers, I obtain certain important advantages. The cutting away of the folding plate or plates, so to speak, and the provisions made for concaving the free portion of the upper ply of the blank makes it unnecessary to time the movements of the various parts relative to one another as accurately as is necessary when the folding plate or plates extend to the main crossfold line and back lash or lostmotion in the gearing or operating connections becomes a matter of much less importance. Moreover, cutting away the folding plate or plates reduces the Weight of and the moment of inertia of the parts of the turning back mechanism which have rclatively rapid but more or less irregular movements.

By preference, I weaken the portion of the ply immediately in front of the main crossfold line as by creasing it prior to the concaving operation in order to facilitate such operation. This facilitates and more or less detern'iines the character of the curvature given to the upper ply of the blank.

The inwent-ion is capable of use in many dili'erent types of machines, but is particularly adapted for use in machines of that. 'ype in which the blank transporting device is a rotating folding cylinder and the tuna ing back mechanism is mounted independently of the folding cylinder to revolve about an aXis parallel to the axis of the folding cylinder. in machines of this type, the use of my invention makes it unnecessary to provide for any definite movements of approach and recession between the axis of the turning back mechanism and the surface of the folding cylinder. Furthermore, the movements of the upper ply gripping devices necessary to engage and release the upper ply may take place so close to the axis of the turning back mechanism that no trouble is experienced in obtaining these movements at high speed.

I have aimed in the claims annexed to and forming apart of this specification to point out with particularity the variousfeaturesof novelty characterizing my invention, but for a better understanding of the in vention and the advantages possessed by it, reference may be had to the accompanying drawings and descriptive matter, in which I have illustrated and described the manner in which the invention is carried out and preferred forms of apparatus used in carrying out the invention.

Of the drawings: Figure 1 is a front view with portions broken away of one form of a rotary bag machine in which my invention is utilized. Fig. 2 is a sectional elevation taken on the line 22 of Fig. 1. Fig. 3 is a diagrammatic side elevation of the machine of Fig. 1 illustrating the manner in which the various rotating elements of the machine are geared together. Fig. 4 is a partial sectional elevation on the line 4% of Fig. 1 showing the means for giving a to and fro rotary movement to the mechanism for engaging and turning back the upper plies of the blanks. Fig. 5 is a plan view of a blank creased by one form of the apparatus shown. Fig. 6 is a partial plan view of a blank creased by another form of the apparatus shown. Fig. 7 is an elevation of the creasing rolls for creasing the blank as shown in Fig. 5. Fig. 8 is a view similar to Fig. 7 showing the modified creasing rolls for creasing the blank as shown in Fig. 6. Fig. 9 is a diagrammatic view illustrating the positions of the upper ply of a blank and the mechanism engaging it during diiferent stages of the folding operation carried out by the machine shown in the drawings. Fig. 10 is a view similar to Fig. 9 illustrating the operation of a machine, differing slightly in its operative movements from that shown in detail. Fig. 11 is a side elevation of a portion of the mechanism illustrating the position of the apparatus for engaging and turning back the upper ply of the blank at the beginning of its operation. Figs. 12, 13, 15 and 16 are views similar to Fig. 11 illustrating the condition of the apparatus in successive stages of the turning back operation. Fig. 14 is a front view of a portion of the apparatus shown in Fig. 13 when in the position shown in the last mentioned figure. Fig. 17 is a view of a portion of the apparatus shown in Fig. 15. and in the cc-n dition shown in that figure. viewed in the direction of the arrow applied to Fig. 15; and Fig. 18 is a view taken similarly to Fig. 18, but on a larger scale.

In the particular machine shown in the drawings. A. represents the base of the machine and A. the side frames, in the latter of which are journaled the creaser rolls B and C, folding cylinder E, transfer rolls D for carrying the blank from the creaser rolls to the cylinder E, and the shaft I of the turning back mechanism. The creaser rolls, the transfer rolls and the folding cylinder are geared together by gears B, C, D, F, F and E and are rotated by suitable driving means not illustrated.

The creaser roll B, in the form shown in Figs. 2 and 7, is provided with a creasing blade B adapted to crease the blank at the main transverse or primary crossfold line indicated at h on the blank M of Figs. 5 and 6, and is also provided with a blade B shorter than the width of the blank for forming a short crease line, M of Fig. 5, in the blank in front of the main crossfold line. In the creasing roll arrangement shown in Fig. 8, the short blade B is replaced by a longer blade B which creases the blank across its entire width, forming the crease line M of Fig. 6. In each construction, the roll C is provided with a creasing block C having a groove C in which the blade 13 enters and a groove C in which the blade B or B enters. I prefer the creaser roll construction of Fig. 7 to that of Fig. 8, as I consider it usually unnecessary to weaken the portion of the blank in front of the main crossfold line, except in the seam portion of the blank.

The folding cylinder E is provided, in the form shown, with two folding bed portions, on each of which a blank may be secured and transported. The two beds and cooperating devices are similar and come into operation alternately. At the front end of each folding bed a front flap holder G is pivoted to the folding cylinder in the usual way. Each holder projects outward through an opening FF formed in the periphery of the folding cylinder and is actuated to clamp and release the front end of the lower ply of the blank in the usual manner by means of a spring G and a cam roll G running on the stationary cam G cimilarly, the folding cylinder is provided at each folding bed portion with a pair of opposed side grippers or tuck holders H which are caused to clamp a blank on the folding bed and release it by means of a spring ,I-I' connecting the opposed pair of grippers H and cam rolls H provided upon each gripper H and bearing against cams H The cams H are carried at the ends of tubular frame portions A surrounding the shaft E of the folding cylinder and supported by frame portions or standards A The tubular frame A at one side of the machine also supports the cam G for actuating the front grippers G.

The mechanism for engaging and turning back the upper ply of the blank comprises a rotary shaft having a flattened or folding plate portion I, fingers J and K for securing the upper ply of the blank against the flattened shaft portion I and mechanism for giving the shaft I and the fingers K the desired operative movements. During the turning back operation, the shaft I is rotated in its bearings through an angle something less than 180". After the com pletion of this rotative movement, the shaft may be returned to its initial position by a continuation of the original rotary movement or by rotating it in an opposite movement. In the form illustrated, the shaft I is given an oscillatory rotary movement instead of a continuous rotary movement by means of a gear Wheel I fixed on one end of the shaft, and a lever I pivoted to the frame work of the machine, and provided with a gear segment I meshing with the gear I, and provided also with a cam roll I working in a cam slot E of a cam member E secured to the shaft E of the rotating cylinder. The cam groove E is shaped to swing the shaft I forward and backward once in each revolution of the folding cylinder for each of the folding beds on the cylinder and with the desired speed. The finger J secured to the shaft I is centrally disposed so as to enter the mouth of the blank between its side edges, and has its entering end J dmvnwardly curved to facilitate the entrance of the finger into the mouth of the blank. The fingers K are similar and are formed with arms K which are journaled about and are slidingly movable along small shafts I s cured in brackets I carried by the shaft I at each side of the folding bed. Each finger K is moved axially of the shaft I by means of a collar K sliclingly mounted on the shaft I and provided with a projection K having forks which straddle the arm K of the finger. The collar K is given reciprocatory movement in the direction of the axis of the shaft I by means of a cam lever K which engages the groove in the collar K and has a cam roll K working in the cam path in the cam member E*. The arm I of each finger K works in a slot formed in a cam member I carried by the shaft I. As a result of this construction, when each [in ger K is moved axially of the shaft I, it is caused to approach and recede from the flattened portion I of the shaft I.

In operation, the tubular bag blanks delivered in regular succession to the creaser rolls B and C are creased by those rolls and delivered by them to the transfer rolls 1) and by the latter are delivered to the folding cylinder. As each blank passes out from between the rolls D, its forward end springs open and the lower ply is clamped onto the folding cylinder by the front gripper G and the side gripping devices I-I, while the curved end J of the finger J entering themonth of the blank deflects the portion of the ply in front of the rear edge of the shaft I out of line with the body of the ply and against the flattened side of the shaft portion I. At the same time the fingers K are moved into the side tucks of the blank and are, during the final portion of their inward movements, carried by the cam members I toward the shaft portion I to clamp the upper ply of the blank against the latter. The fingers K serve as tuck holders and fix the position of the corners of the diamond square in the upper ply of the blank. A. bracket L supports a guide plate L which prevents the upper ply of the blank from having too great an upward movement as it passes from be tween the rolls D.

Fig, 11, Fig. 12, Figs. 13, 1a and 18, Figs. 15 and 17 and Fig. 16 illustrate the condition of the blank and the positions of the folding mechanism at successive stages in the folding operation.

F 11 represents the position of the shaft I during engagentient of the blank by the finger J and at the time in which the fingers K are moved to clamp the blank against the folding plate portion I of the shaft. In Fig. 11, the fingers K are just about to be moved to lift the edges of the upper ply up against the face of the flattened shaft portion I.

Fig. 15 represents the position of the apparatus and the blank when the mouth of the latter is fully distended and the dia- 100 mond fold is formed. The blank may be released from the turning back mechanism after being carried into the position of Fig.

15; it is, however, immaterial whether it is released at that instant, or whether the 105 shaft I had been carried over to the posit-ion shown in Fig. 16, instead of to Fig. 15, and then released. Either plan may be used without materially affecting the operation of the apparatus.

An understanding of the characteristic features in the operation of the mechanism disclosed, and the manipulation of the paper had thereby, may perhaps be facilitated by an examination of Fig. 9, wherein I have 115 illustrated the shape of the upper ply of the blank and the relation between the flattoned shaft portion I and the fingers K relative to the main crossfold line M of the blank during successive stages of the 120 blank folding operation.

In F ig. 9, position 1 corresponds generally to that of Fig. 11, but in Fig. 9 the blank is shown gripped between. the fingers K and the flattened shaft portion I. Po- 125 sitions 4; and 5 correspond to Figs. 15 and 16 respectively, and positions 2 and 3 are intermediate positions corresponding to Figs. 12 and 13 respectively.

It will be observed from position 1 of 13 Fig. 9 as well as from Fig. 11, that the face of the flattened shaft portion 1 is inclined to the body of the upper ply at the instant the upper ply is gripped between it and the fingers K. In consequence, the act of engagement of the upper ply by the turning back mechanism, including the shaft portion I, finger J and fingers K, deflects the portion of the blank engaged into a position parallel to the face of the shaft portion 1 and at an angle to the body of the upper ply, and concaves the portion of the blank between the main crossfold line M and the line M corresponding to the inner edge of the shaft portion 1. This concavity is maintained practically until the mouth of the blank is fully distended, as is illustrated by the drawings. Concaving this portion of the blank prevents it from bowing outward and thereby prevents it from kinking and avoids the formation of false fold lines or wrinkles in this portion of the ply.

Heretofore, the method employed to prevent wrinkling of the upper ply of the blank between the main crossfold line and the corners of the diamond square has been car ried out by positively holding this portion of the blank taut during the turning back operation. Usually a folding plate or plates have been employed for this purpose which extend from the corners of the diamond square to the main crossfold line of the blank, as any other means for positively holding this portion of the blank taut involves additional parts or undesirable strain on the blank material. The use of a folding surface such as is formed by the flattened face of the shaft portion 1, which extends inwardly nearly or quite to the crossfold line M of the blank, necessitates that the corners l of the diamond square in the upper ply of the blank shall travel in a circle (are 20 of Figs. 9 and 10) about the main crossfold line M of the blank as an axis and that the motion of the turning back mechanism about its axis of rotation should be so accurately timed with respect to the motion of the folding bed relative to that axis of rotation that the folding plate extends at all times radially from the main crossfold line M. With the present invention, however, the paths 21 of the corners M of the diamond square are not truly circular about the line M as an axis. and these paths need not be accurately fixed, since the portion of the blank between the lines M and M is entirely unrestrained, except by the rigidity of the blank, and it can accommodate itself to variations in the path 21 of the corners of the diamond square and also to variations in the rate of turning movements of the turning back mechanism about its own axis. In practice, in a given machine, where the corners M of the diamond square travel through a fixed path,

the line M of the upper ply may approach and recede from the axis of the turning back mechanism and the lower ply of the blank during the folding operation, and by preference, I arrange the mechanism so, that when the mouth of the blank is being distended and the crease lines in the side tucks are being straightened out, the line bl in the upper ply is above the lower ply, as such separation of the two plies at the main crossfold line facilitates a proper formation of the diamond fold.

With the actual mechanism shown in the drawings, the initial concaving of the portion of the blank between lines M and l\ accomplished by the action of the finger J and fingers K in clamping the blank against the flattened face of shaft portion 1, occurs prior to the instant when the shaft I begins to rotate to complete the turning back of the upper ply. The rotation of the shaft I is timed, however, so as to maintain this concavity until the diamond fold is practically formed. However, it is, of course, apparent that the initial concaving of the upper ply of the blank as well as the maintenance of this concavity might be had entirely through the rotation of the shaft I or like device, and in Fig. 10 I have illustrated successive positions, 10, 11, 12, 13 and 14:, of the upper ply of the blank and the gripper mechanism engaging it at the corners of the diamond square, in which this gripper mechanism engages the blank when its forward end is in alinement with the body of the blank and is then rotated so as to immediately concave the upper ply and eventually to form the diamond fold.

When a folding plate or plates extending to or nearly to the main crossfold line are employed in a machine of the general type illustrated, in which the turning back mechanism does not revolve bodily with the rotating folding cylinder, it is necessary to carefully time the rotation of the turning back mechanism on its own axis so that at each instant the angular velocity of rotation of the turning back mechanism about its own axis is equal to the angular velocity of the corners of the diamond square through their circular orbits. But with my invention, no attempt is made to get such an equality of motions. On the contrary, the turning back mechanism, and the portion of the upper ply of the blank directly engaged thereby is given a turning back movement during the early portion of each diamond folding operation which is in excess of that simultaneously given to the entire portion of the upper ply turned back and the amount of this excess movement within quite wide limits is immaterial.

The fact, apparent on comparison of Figs. 9 and 10, that variations inathe path of the turning back mechanism, and in the rate at which the portion of the ply g 'ipped by it is turned about the axis of the turning back mechanism, make practically no difference in the formation of the diamond fold, con stitutes one of the most important advantages of my invention. With my invention it is only essential that the turning back mechanism should grip the upper ply at the proper points, that the blank should be re leased at the proper time and that there should be suiiicient concavity in the upper ply to prevent the restrained portion from buckling upward. There must be suflicient concavity to prevent outward buckling, but a considerable excess of concavity over the minimum necessary does not affect the operation of the mechanism. In consequence, the use of my invention simplifies the construction and improves the operation of bag machines, not only because the mechanism for giving motion to the turning back meclr anism need not be so accurately designed initially, but also because the effect of lost motion or back lash. in the driving connections is a matter of little importance.

Aside from the advantages just referred to, the use of a folding plate such as is formed by the flattened shaft portion l, which does not extend to, or close to, the main crossfold line of the blank, has impor tant practical operating advantages, from the fact that it reduces the weight of the turning back mechanism, and particularly, because it reduces the moment of inertia of the turning back mechanism about its axis of rotation. This, of course, is a material. aid in obtaining satisfactory operation at high speed.

It will be observed also that the fingers K are located close to the axis of the shaft 1 and hence their proper to and fro move ments in engaging and releasing the blank are readily had regardless of the speed at which the machine operates.

, With my invention there is an advantage, also, from the fact that the turning back mechanism need turn in each diamond folding operation through an angle substantially less than 180. This is particularly true with apparatus operating in accordance with Fig. 9. The reduction in the amount of angular movement of the turning back mechanism during a diamond folding operation means relatively slower turning movement of the turning back mechanism, which is an advantage, of course.

While, in accordance with the provisions of the statutes, I have herein illustrated and described the best forms of my invention and the best modes of carrying it out now known to me, it will be understood by those skilled in the art that many changes may be made in the form of the apparatus disclosed without departing from the spirit of my invention, and I do not wish the claims hereinafter made to be limited to the particular embodiments disclosed more than is made necessary by the state of the art.

Having now described my invention, What I claim as new and desire to secure by Letters Patent is:

1. In a machine for diamond folding a tucked bag blank, the combination with means for engaging the lower ply of, and transporting, the bag blank, of cooperating mechanism for opening the end of the blank and turning back its upper ply, comprising devices adapted to ei'igage the upper ply of the blank at the corners of the diamond square while leaving a portion of the ply between the main crossfold line and the portion engaged by said mechanism free to accommodate itself to the stresses set up in it during the folding operation, and means opcrating said devices to give said engaged portion of the upper ply a turning back movement during an early stage of the folding operation, which is in excess of that given to the entire portion of the upper ply turned back, whereby the upper ply of the blank is concaved during said early stage and is thereby prevented from kinking.

2. in a machine for diamond folding a tucked bag blank, the combination with means for engaging the lower ply of, and transporting, the bag blank, of cooperating mechanism for opening the end of the blank and turning back its upper ply, comprising devices adapted to engage the upper ply of the blank at the corners of the diamond square while leaving a portion of the ply between the main crossfold line and the portion engaged by said mechanism free to accommodate itself to the stresses set up in it during the folding operation, and. means for operating said devices to give said engaged portion of the upper ply a turning back movement during an early stage of the folding operation, which is in excess of that simult-aneously given to the entire portion of the upper ply turned back, whereby the upper ply of the blank is concavod during said early stage and is "thereby prevented from kinking, and means for weakening the por tion of the ply concaved to facilitate such concaving.

3. In a machine for diamond folding a tucked bag blank, the combination with means for engaging the lower ply of, and transporting, the bag blank, of cooperating mechanism for opening the end. of the blank and turning back its upper ply, comprising devices adapted to engage the upper ply of the blank at the corners of the diamond square while leaving a portion of the ply between the main crossfold line and the portion engaged by said mechanism free to accommodate itself to the stress set up in it during the folding operation, and means for operating said devices to give said engaged portion of the upper ply a turning back movement during an early stage of the folding operation, which is in excess of that given to the entire portion of the upper ply turned back, whereby the upper ply of the blank is concaved during said early stage and is thereby prevented from kinking and means for creasing the blank in front of the crossfold line prior to the concaving operation.

4. In a machine for diamond folding a tucked bag blank, the combination with means for engaging the lower ply of, transporting, the bag blank, of cooperating mechanism for opening the end of the blank and turning back its upper ply, comprising devices adapted to engage the upper ply of the blank at the corners of the diamond square while leaving a portion of the ply between the main crossfold line and the portion engaged by said mechanism free to accommodate itself to the stresses set up in it during the folding operation, and means operating said devices to give said engaged portion of the upper ply a turning back movement during an early stage of the folding operation, which is in excess of that simultaneously given to the entire portion of the upper ply turned back, whereby the upper ply of the blank is concaved during said early stage and is thereby prevented from kinking, and means for creasing the blank at the crossfold line and in front of the crossfold line prior to the concaving operation.

5. In a machine for diamond folding a tucked bag blank, the combination with the diamond folding mechanism, of mechanism cooperating therewith to transversely crease each blank passing to said folding mechanism at the line at which the folding mechanism forms the main crossfold line in the blank, and in front of said line at a distance therefrom substantially less than the blank tuck depth.

6. In a machine for diamond folding a tucked bag blank, the combination with the diamond folding mechanism, of mechanism cooperating therewith to transversely crease each blank passing to said folding mechanism at the line at which the folding mechanism forms the main crossfold line in the blank, and in front of said line at a distance therefrom substantially less than the blank tuck depth, the last mentioned mechanism comprising a roll having a creasing blade adapted to crease the blank at and along the length of said main crossfold line and hav ing a second creasing blade for creasing the blank in front of said main crossfold line, said second creasing blade being shorter than the width of the blank and adapted to form a crease line in the blank between its side edges and parallel to said main crossfold line.

7. In a machine for diamond folding a tucked bag blank, the combination with a rotary folding bed and means for securing the lower ply of the bag blank thereon, of gripping mechanism for engaging the upper ply of the blank at the corners of the diamond square and turning it back while leaving a portion of the blank between the main crossfold line and the gripping mechanism engaged portion of the blank free to accommodate itself to the stresses set up in it during the folding operation, supports in which said gripping mechanism is mounted to turn about a stationary axis, and means for causing the gripping mechanism to engage the upper ply of the blank and for rotating said mechanism in its support in such manner that the portion of the blank engaged by the gripping mechanism is given a turning back movement during an early stage of the folding operation which is in excess of that simultaneously given to the entire portion of the upper ply turned back, whereby the upper ply of the blank is concaved during said early stage and is thereby prevented from kinking.

8. In a machine for diamond folding a tucked bag blank, the combination with a folding bed and means for securing the lower ply of the bag blank thereon, of a rotary folding plate, fingers for entering the side tucks of the blank and clamping the upper ply against the folding plate, means for actuating the fingers, and means for r0- tating the folding plate, arranged to hold the plate at an angle to the direction of the blank when the upper ply is clamped against it, whereby the portion of the ply between the folding plate and the main crossfold line of the plate is concaved, and to thereafter move the folding plate in such manner as to maintain the concavity in the upper ply during an immediately following portion of the folding operation.

9. In a machine for diamond folding a tucked bag blank, the combination with means for engaging the lower ply of, and transporting, the bag blank, of cooperating mechanism for opening the end of the blank and turning back its upper ply, comprising a rotating gripper mechanism adapted to engage the upper ply of the blank at the corners of the diamond square while leaving a portion of the ply between the main crossfold line and the portion of the ply engaged by said mechanism free to accommodate itself to the stresses set up in it during the folding operation, means for actuating said gripper mechanism in such fashion that the portion of the ply engaged is deflected from the line of the body of the blank and the upper ply of the blank is concaved in front of the crossfold line, and means for moving said mechanism bodily to maintain the concavity during a following portion of the folding operation.

10. In a machine for diamond folding a tucked bag blank, the combination with a rotating folding cylinder and means for securing a tucked bag blank thereon, of a folding plate extending parallel to the axis of the folding bed, supports in Which said folding plate is mounted to turn about an axis parallel to the axis of the folding bed, fingers connected to said folding plate, means for moving said fingers to cause them to enter the side tucks of the blank and clamp the upper ply of the blank against the folding plate, and means for rotating said folding plate in its supports, arranged to hold the folding plate at an angle to the body of the upper ply of the blank at the instant at which the fingers clamp the latter against the plate, and a centrally disposed finger carried by the folding plate adapted to enter the mouth of the blank and bring its upper portion into parallelism With the folding plate.

l/VILLIMI A. LORENZ. WVitnesses:

LOUIS BEI-INER, VVHITMonn EMMoNs.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of latents.

Washington, I). G. 

